^m: 386 



GEOLOGICAL COLLECTIONS. 



Notice of the Discovery of the Plesiosaurus in Ireland. By James Bryce, 

 Jun. A.B. — It is well known to geologists, that the oolites, — that series 

 of rocks which, in England, intervenes between the new red sandstone and 

 the chalk, — are almost entirely wanting in Ireland. The only members of 

 the formation which exist there, are the lias and the mulatto, or green-sand, 

 and these occupy but a very limited extent of surface. They ai)pear in the 

 escarpment of the great basaltic area, which comprehends all Antrimand 

 half of Derry. Encircling it, the chalk, with one or two exceptions, aways 

 underlies the basalt. The mulatto generally accompanies it ; but the lias 

 is frequently absent. It occupies a narrow though unbroken zone from a 

 few miles south of Belfast, to two miles north of Same, — a distance of 

 about twenty miles ; but in the remaining part of the escarpment it occurs 

 only in detached patches of very small extent. Limited, however, as the 

 formation is, it has been but partially examined, and until within the last 

 few months it has not afforded any remains of the vertebrate animals, which 

 have been found in such abundance in the same formation in England. 

 Within that time, some vertebrae of the plesiosaurus have been discovered 

 near Belfast. 



These remains were found in the black clay of the lias which underlies 

 the mulatto along the southern front of the low hills which connect the 

 Cave-hill with Carnmoney-hill, at the distance of four miles northeast of 

 Belfast. The stratum is beautifully exposed in section in a chalk quarry 

 within a few perches of Carnmoney church : in this quarry the vertebrae 

 were found. Twelve of them were lying in a straight line in groups of two 

 or three together, which were separated from one another by an interval 

 of about a yard and a half, thus shewing that they were remote parts of the 

 same vertebral column. They were all carried off by the workmen ; and, 

 with the exception of one, which, after the strictest search, was recovered, 

 they were all lost. Six more were afterwards found, under such circum- 

 stances as to render it highly probable that they belonged to the same 

 individual as the former. These seven vertebrae are now deposited in the 

 Museum of the Belfast Academy.* 



Being acquainted with the discoveries of Sir Everard Home and the 

 Rev. W. D. Conybeare, I suspected that they belonged either to the 

 Ichthyosaurus or to the Plesiosaurus ; but knowing no more of comparative 

 anatomy than enabled me to comprehend the terms of a description, I had 

 recourse to the memoirs published in the Geological Transactions, (vol v. 

 part ii., and, second series, vol. i. parts i. and ii.) by Mr Conybeare, to 

 whose sagacity we owe almost all our knowledge concerning these singular 

 genera. On comparing the vertebrae with his drawings and descriptions, it 

 was evident that they belonged to the Plesiosaurus. Two of them are 

 cervical, four dorsal, and one lumbar. They were recognized by being 

 slightly concave at both ends, by the proportions which obtain between the 

 length of the side and the diameter Of the articulating surface, by small 

 dimples in the lower part of the body, and by a slight swelling in the middle 

 of the circular area of the end, which is largest in the dorsal, and in the 

 lumbar does not at all exist. The spinous processes are almost entirely 

 broken off; so much of them remains as barely to shew the course of the 



* They were presented to the Museum by Mr J. H. Smythe, of Carnmoney, to whom 

 the credit of their discovery is due. 



